32 MASS. EXPERIMENT STATION BULLETIN 293 



has been reported in any year of its present period of abundance. The peak of 

 emergence of flies was later than normal, and the flies were active in the orchards 

 over a much longer period than usual. This was largely associated with the very 

 light rainfall during late spring and early summer which left the soil dried and hard 

 packed, a condition very unfavorable for the emergence of the flies. Under such 

 circumstances proper timing of the sprays was difficult. 



In the demonstration orchards where the growers were devoting especial atten- 

 tion to maggot control and carried out a complete control program, the pest was 

 held to an average of less than 1 per cent damage. In the 14 blocks from which 

 records were taken, 4 showed no fruit injured by maggot, and in 4 others the num- 

 ber of injured apples was 3 or less. In 7 of the blocks the fruit scored 85 per cent 

 clean or higher, and in every case maggot injury was held to a lower figure than 

 that of any other major pest. 



One of the outstanding features of the season's work was the influence of orchard 

 environment or, in other words, the necessity of proper treatment of neglected 

 trees or orchards surrounding commercial blocks. Many growers found that even 

 with the most thorough program possible they could not control maggot in their 

 orchards because of the exposure of their blocks, on one side or more, to neglected 

 apple trees. 



The experience of the past season demonstrated that growers in whose orchards 

 apple maggot is a problem must take suitable precautions to clean up their orchard 

 surroundings, since the influence of orchard environment is in most cases the 

 limiting factor determining satisfactory control of the insect or complete failure. 



Introduction of Parasites of Oriental Fruit Moth. (A. I. Bourne.) Duri ng 

 the last two years the Department of Entomology has cooperated with the U. S. 

 Bureau of Entomology in the introduction and establishment of parasites of the 

 Oriental fruit moth. Colonies of Macrocentrus ancylivorus were liberated in 

 peach orchards throughout Hampden County where the infestation of fruit moth 

 was sufficient to allow the establishment of the parasites. 



Recoveries from twig collections indicated that the parasites were able to sur- 

 vive the winter of 1931-32 in Hampden County and build up a considerable 

 population in the peach orchards the following spring. In orchards where libera- 

 tions were made in 1931, a considerable reduction was noted in early twig injury 

 the following spring, and growers reported beneficial results on the basis of the 

 crop at harvest. 



If a sufficient supply of parasites can be obtained, more extensive liberations 

 will be made another season in other peach-growing sections of the State into which 

 the fruit moth has now spread. 



Plum Curculio. (W. D. Whitcomb.) Studies of the plum curculio under 

 controlled temperatures maintained at 55°, 65°, 75°, and 85° F. were continued 

 with special attention to influence of temperature on oviposition. The activity 

 of ten pairs of mated beetles at each temperature was recorded daily. 



The number of eggs laid increased at each higher temperature in an approximate 

 ratio of 1 :5 :9 :12, and about 75 per cent of the eggs were laid during the first 20 days 

 of oviposition regardless of the temperature. Slightly more eggs were laid in the 

 first 10 days than later but the ratio of egg punctures to feeding punctures was 

 about 4 per cent greater in the second 10-day period. At each temperature the 

 last eggs were laid about 55 days after oviposition began. The average number of 

 eggs per female per day laid during the first 20 days was 0.72 at 55°, 3.44 at 65°, 

 and 10.21 at 85° F. The maximum number of eggs laid during life by one female 



